Gene dosage is important is an important issue both in cell and evolutionary biology.Most genes are present in two copies in eukaryotic cells. The first outstanding exception is monoallelic gene expression (MA) that concerns genes localized on the X chromosome or in regions undergoing parental imprinting in eutherians, and many other genes scattered throughout the genome. The second exception concerns haploinsufficiency (HI), responsible for the fact that a single functional copy of a gene in a diploid organism is insufficient to ensure a normal biological function. One of the most important mechanisms ensuring functional innovation during evolution is Whole genome duplication (WGD). In addition to the two WGDs that have occured in vertebrate genomes, the teleost genomes underwent an additional WGD, after their divergence from tetrapods. In the present work, we have studied on 57 teleost species whether the orthologs of human MA or HI genes remain more frequently in duplicates or returned more frequently in singleton than the rest of the genome. Our results show that the teleost orthologs of HI human genes remained more frequently in duplicate than the rest of the genome in all the teleost species studied. No signal was observed for the orthologs of genes localized on the human X chromosome or subjected to parental imprinting. Surprisingly, the teleost orthologs of the other human MA genes remained in duplicate more frequently than the rest of the genome for most teleost species. These results suggest that the teleost orthologs of MA and HI human genes also undergo selective pressures either related to absolute protein amounts and/or of dosage balance issues. However, these constraints seem to be different for MA genes in teleost in comparison with human genomes.

中文翻译：

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编码人类单倍体不足和单等位基因的硬骨直向同源物的基因比整个基因组更频繁地重复

基因剂量对于细胞生物学和进化生物学都是重要的问题。大多数基因在真核细胞中以两个拷贝存在。第一个突出的例外是单等位基因表达（MA），它涉及X染色体上或在以太子中受到亲本印记的区域中的基因，以及分散在整个基因组中的许多其他基因。第二个例外涉及单倍体功能不全（HI），其原因是二倍体生物体中基因的单个功能拷贝不足以确保正常的生物学功能。确保进化过程中功能创新的最重要机制之一是全基因组复制（WGD）。除了在脊椎动物基因组中出现的两种WGD外，硬骨鱼基因组与四足动物不同后，还要进行另外的WGD。在目前的工作中，我们已经研究了57种硬骨鱼物种，与其他基因组相比，人类MA或HI基因的直系同源物是否更频繁地重复出现或单倍返回。我们的结果表明，在所有研究的硬骨鱼物种中，HI人类基因的硬骨直向同源物一式两份比其余基因组更经常出现。没有观察到位于人X染色体上或经历过亲本印迹的直系同源基因信号。令人惊讶的是，对于大多数硬骨鱼物种而言，其他人类MA基因的硬骨直向同源物比基因组的其余部分更频繁地重复出现。这些结果表明MA和HI人类基因的硬骨直向同源物也经受与绝对蛋白质量和/或剂量平衡问题有关的选择性压力。然而，